"As far as the agreements about the future institutional organization in the eurozone are concerned, I'm very disappointed," Jacques Delors told the German broadcaster Deutsche Welle. "The end result resembles a machine with a thousand intricate parts. New groups and new presidential positions are being created, but how it all is supposed to work remains unclear."
Delors, who was president of the commission from 1985-1994, said the plan to halve Greece's debt and increase the main bailout fund to $1.4 trillion was "solid."
"The banks accepted a big sacrifice on their parts to save Greece. Given the situation, that's about the best you can hope for," he said.
But he said steps to be taken throughout the eurozone "were negotiated like a poker game among the EU members."
"That sort of went against the method of working as a community," Delors said. "In that sense, the European Commission was pushed aside. Now there are four or five groups. The EU is divided.
"But the community approach has proved itself in the past: Europe has made progress when it was used. That's the only method that is simple and efficient. It forces the governments to make decisions together."
Delors said the summit had to "put out the fire burning in the eurozone but the community of Europe has suffered and the commission has suffered a loss of authority."
Delors played a major role in EU integration, the creation of a single European market and the treaty that turned the European Community into the European Union in 1992.